As described in U.S. patent application Ser. No. 11/149,883, of Maa et al., filed Jun. 10, 2005, for Method of Fabricating a Low-defect Strained Epitaxial Germanium Film on Silicon, a cyclic anneal of a germanium film on silicon effectively reduces the defect density and moves the defects to the bottom of germanium film near the germanium/silicon interface.
Masini et al., High-performance p-i-n photodetectors for the near infrared: from model to demonstration, IEEE Trans. Electron Devices, vol. 48, pp 1092-1096 (2001), describes calculation of dark current density, based on the band diagram and the defect on the germanium/silicon interface.